1. Field of the Invention
The present invention relates to a holographic display apparatus which is applied to vehicle parts such as high mounted stop lamps and direction indicators.
2. Description of the Prior Art
Recently, many automotive vehicles have been provided with high mounted stop lamps to a rear window directly or in the vicinity of it. An integrated type of a luminous source and a housing is mainly used as a high mounted stop lamp. However, such stop lamps are complex and may impose limitations on the design of the automobile. Such stop lamps further include drawbacks such as the decrease of the backward visibility of a driver and the decrease of a free space in the vehicle compartment. In order to improve such drawbacks, a holographic sheet including transparent type holograms has been proposed as a display element of high mounted stop lamps.
However, such a holographic display element yet includes drawbacks that in the event that a point luminous source such as a bulb is used as a luminous source, the element cannot clearly project whole image of the holograms of the holographic sheet, for example, although a central portion of the holographic sheet is light but the peripheral portion of it is dark.